1. Field of the Invention
The present invention relates generally to an exhaust pipe structure of a hybrid vehicle with a driving battery pack equipped under the vehicle body.
2. Description of the Related Art
In recent years, a hybrid vehicle utilizing both an internal combustion engine and an electric motor at least one of which is used for driving power of the vehicle is known publically. Such a hybrid vehicle is disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. H11-178111 (JP H11-178111-A) and Jpn. Pat. Appln. KOKAI Publication No. 2011-011647 (JP-2011-011647-A).
In such a hybrid vehicle, the internal combustion engine and the electric motor such as a motor generator, etc. are mounted at the front side of the vehicle and the driving battery pack is mounted at the rear side of the vehicle. To suppress fuel consumption as low as possible, use of the internal combustion engine is required to be minimized for driving the vehicle. It is thus desired that the vehicle is driven by the electric motor as much as possible. For this reason, the battery volume is enlarged in a hybrid vehicle, and the size and weight of the driving battery pack are increased.
The driving battery pack requires a protection against damage caused by external stress in case of collision with the other object, etc. Especially, since a catalytic part on an exhaust pipe is very solid and heated to high temperatures, possible damage caused by the catalytic part interfering with the driving battery pack must be avoided.
The exhaust pipe is connected to the internal combustion engine at the front side of the vehicle and is extended to the rear side of the vehicle passing under the vehicle body. Therein, as disclosed in JP H11-178111-A, the exhaust pipe may be arranged in the vehicle such that the catalytic part on the exhaust pipe does not overlap with the battery pack when being viewed either from the front of the vehicle or from the sides of the vehicle.
However, when efficient purification of exhaust gas from the internal combustion engine is taken into consideration, it is desirable that, as disclosed in JP 2011-011647-A, a three-way catalyst is provided near the exhaust pipe structure so that the three-way catalyst can be heated up by the exhaust gas for better gas reduction performance. Despite such a technical desire, JP 2011-011647-A does not disclose a positional relationship between the driving battery pack and the three-way catalyst or a technique to secure safety therebetween in case of a collision.
In the hybrid vehicle described above, in order to place the three-way catalyst in a position adjacent to the internal combustion engine, it is necessary to dispose the three-way catalyst in a position to overlap with a front wall of the battery pack, that is, a position between the internal combustion engine and the battery pack. However, in such a position, the three-way catalyst will interfere with the battery pack if the vehicle collides head-on with an object, and consequently, the battery pack will be damaged.